Prior to this invention, it has been known to make neopentyl glycol (2,2 dimethyl-1,3-dihydroxypropane, also known herein as NPG) by reacting formaldehyde with isobutyraldehyde and hydrogenating the resulting hydroxypivaldehyde (HPA). See U.S. Pat. No. 4,855,515, for example, which recites the historical development of the reaction and emphasizes the use of a particular catalyst in the hydrogenation step. U.S. Pat. No. 3,808,280 discloses the use of triethylamine as a catalyst for the (aqueous) formaldehyde/isobutyraldehyde reaction.
Each of the above references employs formaldehyde in the form of aqueous formaldehyde.
Paraformaldehyde is used by Snam S.p.A. in UK Patent 1,017,618 to react with isobutyraldehyde in the presence of a tertiary amine to produce a reaction product containing apparently predominantly hydroxypivaldehyde which may be hydrogenated to neopentyl glycol. No reference to our knowledge teaches the use of one or more oxides of elements of Groups IB, IVA, IVB, VA, VB, VIB and VIII of the periodic table and paraformaldehyde with the accompanying advantages as explained below. Nor are we are of the use of metal oxide as a catalyst in such a reaction.